Thanks for your question As you have said you have an over active thyroid which is medical terms is known as hyperthyroidism....your reports would include tsh free to t3 and t4. ..tsh would be typically low with elevated t3 and t4..methimazole and propanolol both are given in hyperthyroidism for different indications...While methimazole will act on thyroid receptors and control symptoms of increased metabolism diarrhoea fertility related issues etc..propanolol will dectease the heart rate and other cardiac symptoms which occurs due to hyperthyroiditis. ...Both are safe drugs and should be taken....heart attack will habe different presentation and symptoms as extreme chest pin radiating to back or jaw. ... hope this solves your query